It is known to outfit a motor vehicle with a display system, known as a heads-up display. Such a system is placed in the field of vision of the driver of the vehicle and it displays one or more pieces of information regarding the state of the vehicle, the traffic, or something else.
This type of heads-up display for a motor vehicle requires the obtaining of an image with sufficient luminosity for the user, and especially the driver of the vehicle, to be able to see the image sufficiently, and in every situation, according to the weather conditions and/or the time of day.
Among the possible technologies for forming such an image thanks to the display the technology most often used in the prior art is that of a liquid crystal screen, particularly a thin film transistor liquid crystal screen (TFT-LCD). These TFT-LCD screens in order to display an image require a back-lighting provided by a light source, generally by a plurality of light-emitting diodes (LEDs). In practice, this TFT-LCD screen and the back-lighting are comprised in an assembly known as an image projection system.
Even so, these TFT-LCD screens have the drawback of reducing in substantial manner the luminous power coming from the back-lighting: with the use of a classical TFT-LCD screen, it is estimated that the transmission level of the screen is around 5% of the luminous power of the back-lighting. This low value is due in particular to the first polarizer present in the screen, which only lets through the light corresponding to a certain polarization, whereas the LEDs produce light with several polarizations: thus, all the polarizations not corresponding to the one let through by the polarizer are lost.
Hence, in order to display an image by the display with a sufficient luminous power, it is necessary to use a back-lighting of significant luminous power, since the image displayed will have a luminous power of the order of 5% of this back-lighting power. This results in significant energy consumption, as well as significant losses in the form of heat, which furthermore may degrade the components and thus require the use of bulky heat dissipators.